Active rear sense area adjustment of collision avoidance system of a vehicle when vehicle is approaching a positive road grade change
In an aspect, false alerts in a collision avoidance system of an automotive vehicle are prevented when the vehicle is in reverse. The collision avoidance system includes at least an upper rear facing obstruction sensor and a lower rear facing obstruction sensor. When the vehicle is approaching a positive road grade change, the sensitivity of the lower rear facing obstruction sensor is reduced. In an aspect, an active rear view area of a rear facing vision system of the vehicle is adjusted when the vehicle is approaching a change in road grade.
1. A method of preventing false alerts in a collision avoidance system of an automotive vehicle when the vehicle is in reverse, the collision avoidance system having at least an upper rear facing obstruction sensor, a lower rear facing obstruction sensor, and an electronic control unit, the method comprising:
having the electronic control unit reduce a sensitivity to an object of the lower rear facing obstruction sensor when the vehicle is approaching a positive road grade change to reduce a distance at which the lower rear facing obstruction sensor senses the object.
2. The method of claim 1 wherein reducing the sensitivity of the lower rear facing obstruction sensor includes reducing its sensitivity by an amount based upon a difference in a current road grade and the approaching road grade.
3. The method of claim 2 further including adjusting an active rear view area of a rear facing vision system of the vehicle when the vehicle is approaching a change in road grade.
4. The method of claim 3 wherein adjusting the active rear view area includes, adjusting the active rear view area by RCAA=(α−β)/α where RCAA is the rear active viewing area, α is the angle from a vision sensor of the rear facing vision system to ground and β is a the difference between the current road surface and the approaching road grade where β is greater than or equal to zero and when the vehicle is traveling in reverse uphill, adjusting the rear active viewing area by RCAA=(α+β)/α where β is less than zero.
5. A vehicle having a collision avoidance system with false alert prevention when the vehicle is in reverse, comprising:
the collision avoidance system having an electronic control unit coupled to upper and lower rear facing obstruction sensors of the vehicle, a rear facing vision system of the vehicle and to a display in the vehicle; and
the electronic control unit configured to reduce a sensitivity to an object of the lower rear facing obstruction sensor when the vehicle is approaching a positive road grade change to reduce a distance at which the lower rear facing obstruction sensor senses the object.
6. The vehicle of claim 5 wherein the electronic control unit is configured to reduce the sensitivity of the lower rear facing obstruction sensor based upon a magnitude of the positive road grade change.
7. The vehicle of claim 6 wherein the electronic control unit is configured to adjust an active rear view area of a rear facing vision system of the vehicle when the vehicle is approaching a change in road grade.
8. The vehicle of claim 7 wherein the electronic control unit is configured to adjust the active rear view when a rear of the vehicle is facing downhill on the current road surface by RCAA=(α−β)/α where RCAA is the rear active viewing area, α is the angle from a vision sensor of the rear facing vision system to ground and β is a magnitude of the change in road grade where β is greater than or equal to zero, and when the rear of the vehicle is facing uphill on the current road surface road adjusting the rear active viewing area by RCAA=(α+β)/α where β is less than zero.